Manufacture of high antiknock



A. R. GOLDSBY IIANUFACTUE OF'- HIGH ANTIKNOCK .HYDROCARBONS Original Filed JulyV 8, 1939 oct. 2o, v1942.

Reissued Oct. 20, 1942 l MANUFACTURE 0F HIGH ANTIKNOCK HYDROCARBON S Arthur R. Goldsby,.Beacon, N. Y.,.assigncr to The Texas Company, a corporation of -Delaware Original No. 2,257,074, dated September 23, 1941,

Serial N0. 283,429, July 8, 1939.

Application for reissue April 14, 1942, Serial No. 438,928

5 Claims. y(-IJl. 1536-10) This invention relates to a process for manufacturing hydrocarbons, such as high anti-knock yhydrocarbons suitable for motor fuel.

The invention broadly contemplates catalytically converting a mixture of carbon monoxide and hydrogen to hydrocarbons and alkylating the .resulting hydrocarbons, or constituents thereof, with isoparain hydrocarbons in the presence of an alkylation catalyst, such as concentratedv sulphuric acid.

It has been known heretofore to produce low- 4boiling hydrocarbons for use in the manufacture of motor fuel by the catalytic conversion of a gaseous `mixture of carbon monoxide Aand hydrogen. The gasoline fraction from the product of conversion contains a large proportion of unsaturated hydrocarbons and is also characterized vby Ahavingya low octane number (C. F. R. M.) of around 40.

It vhas been found that a synthetic hydrocarbon mixture prepared by the conversion of carbon monoxide and hydrogen, such as in a Fischer-Tropsch process, is particularly suitable for alkylation with isoparaflin hydrocarbons, such as isobutane, to produce a saturated motor vfuel which is gum and color-stable, has .a high lead susceptibility and may be of higher anti-knock value. By high lead susceptibility it is meant that the alkylated hydrocarbon mixture is highly susceptible to increase in anti-knock value by incorporating therein lead tetraethyl.

In accordance with the present invention a low-.boiling hydrocarbon mixture is produced, by

the catalytic conversion ofcarbon monoxide and hydrogen, which contains a relatively high content of normal oleiins as the olenic constituent thereof, particularly a relatively high content of normal butylenes `and a relatively low content of isobutylene as the C4 olenic constituents thereof. In addition, the synthetic hydrocarbon mix- `ture is substantially free from aromatic constituents and comparatively free from naphthenic constituents.

An olen containing hydrocarbon mixture which is low in isobutylenecontent is of particu- Likewise, substantial freecomprising a flow diagram illustrating amethod of carrying koutthe process of this invention.

Carbon monoxide and hydrogen or a gaseous mixture thereof in suitable proportions'is passed to a catalytic converter I wherein the gaseous mixture is brought into contact with a conversion catalyst to effect conversion into hydrocarbons having a substantial olen content. The catalyst may comprise metals such yas cobalt, nickel, iron, manganese or the oxides thereof, withor without a promoter `such as thorium oxide. The catalyst is advantageouslysupported upon a material such as diatomaceous earth. Nickel, for example, is a preferred catalyst from the standpoint of increasing the olen production relative to the production of saturated hydrocarbons.

The carbon monoxide and hydrogen may be charged to the converter in the `ratio of around 1 mol of carbon monoxide to about 2 mols of hydrogen. By decreasing somewhat the ratio of hydrogen to .carbon monoxide it is possible to increase the yield of olens produced.

The temperature maintained within the converter may range from around 330 to 400 F. and the reaction may be carried out under a pressure of about atmospheric, although somewhat higher pressures may be employed up to about ten atmospheres, for example.

Instead of a single converter the reaction may be carried out in sta-ges, using two or more converters in series. The products of conversion comprise normally gaseous and normally vliquid hydrocarbons -composed of around 60 to 70% by weight o'f hydrocarbons containing from one to about ten carbon atoms, with the remainder comprising higher boiling hydrocarbons.

The hydrocarbon products of reaction, including Aunreacted carbon monoxide and hydrogen, are passed to a stabilizer 2 wherein the unreacted materials, hydrogen vand carbon monoxide, are removed in the 'form of a gas through a valVed pipe `3 and may be recycled ultimately to the ,converter 'L In cases wherethere is an appreciable `quantity of methane, ethane and ethylene present it is desirable to remove these C1 and C2 hydrocarbons from the conversion products.

The liquid accumulating in the bottom of the stabilizer 2 comprises the synthetic hydrocarbon mixture and is continuously drawn olf through a conduit! and passed to a fractionator 5.

`In the fractionator `5 the synthetic hydrocarbon mixtureis separated into a normally gaseous hydrocarbon fraction, which is removed in Vapor form from the top of `the fractionator. A side stream 'is Aremoved from the fractionator 5 and which comprises normally liquid gasoline hydrocarbons; that is hydrocarbons boiling up to about 392 F.

The higher boiling constituents accumulate in the bottom'of the fractionator 5 and are continuously withdrawn through a valve pipe B.

The gaseous hydrocarbon fraction removed from the top of the fractionator may amount to 8 or 10% of the synthetic hydrocarbon mixture charged to the fractionator. It will comprise hydrocarbons such as propane, butane, propylene and butylene, and the olefin content may be around 50 to 55% by volume.

The liquid gasoline fraction drawn oif as a side stream may amount to around 60% of the synthetic hydrocarbon charge and may contain around 30 to 35% of oleiins.

The gaseous fraction is passed to an alkylation unit 1 wherein it is treated with isobutane in the presence of concentrated sulphuric acid. Thus, fresh isoparaflin may be introduced to the alkylation unit from a pipe 8, while acid is introduced from a pipe 9. The mixture is subjected to reaction within the unit whereby the olefin hydrocarbons are alkylated with the isoparafns.

The used or spent acid is drawn oi, while the alkylate is drawn 01T through a conduit I0 to a neutralizer Il. In the neutralizer Il the alkylate is treated with alkali to neutralize it. The alkali sludge is drawn off while the neutralized alkylate is separately passed through a conduit I2.

Likewise, the liquid gasoline hydrocarbon fraction produced as a side stream from the fractionator 5 is passed to an alkylation unit I3 wherein it is treated with isoparaim in the presence of the alkylation catalyst.

The resulting alkylate is drawn off through a conduit Ill to a neutralizer I5 wherein it is neutralized with alkali. The neutralized alkylate from I5 is drawn off through a conduit I6. While separate alkylation systems are disclosed for the `normally gaseous and the normally liquid conversion products respectively, it is to be understood that the entire conversion product or a fraction thereof cut below about 400 F. and containing both normally gaseous and liquid products may be aikylated in a single alkylation system.

Both conduits I2 and IE communicate with a conduit I1 leading to a stabilizer I8 wherein a gaseous fraction comprising propane may be removed. A fraction comprising normal butane and unreacted isobutane may be removed as a side stream. A portion of the normal butane may be left in the alkylate or subsequently returned thereto in order to adjust the lower end of the distillation range of this product.

The side stream from the stabilizer I8 is introduced to a fractionator I9 wherein the isobutane is separated from the normal butane and other hydrocarbons which may be present.

The isobutane separated in fractionator I9 is passed through a cooling and condensing coil 20 to a conduit 2I, communicating with pipe 8 previously referred to. In this way the unreacted isobutane is recycled to the reaction zone for further reaction with olefin hydrocarbons. Through'a bypass 21 the isobutane may be conducted to the alkylation unit I3.

The liquid alkylate from the bottom of the stabilizer I8 is passed to a fractionator 22, wherein it may be subjected to fractionation to produce a product of the desired distillation range and suitable as a motor fuel. This may be an aviation gasoline having an end boiling point of Aabout 311 F., or a conventional motor fuel having about a 400 F. end point, or may even include higher boiling materials within the kerosene boiling range and suitable for use as a safety motor fuel. The motor fuel product is removed from the top of the fractionator 22 as a vapor and passed through a cooling and condensing coil 23. The resulting condensate is accumulated in a receiver 24.

The higher boiling constitutents are withdrawn in liquid form from the bottom of the fractionator 22 for such disposition as may be desired.

That portion of the normal butane drawn koi from the bottom of the fractionator I9 and not disposed of as such may be conducted to an isomerization plant 25. In the plant 25 it is brought into contact with a suitable isomerization catalyst, such as aluminum chloride, under conditions of temperature and pressure adapted to convert normal butane to isobutane. For example, the normal butane may be subjected to contact with anhydrous aluminum chloride in the presence of a small amount of hydrogen halide in the vapor phase at temperatures of about 190 to 220 F. and pressures of about 175 to 250 pounds per square inch. The off-gases from this reaction may be either recycled in toto, with washing to remove hydrogen halide, or subjected to fractionation. l

The isobutane produced in this way is passed through a pipe 26, communicating with pipe 2| previously referred to, which in turn communicates with pipes 8 and 21 previously referred to.

While alkylation of the synthetic hydrocarbons with isobutane has been specifically mentioned in connection with the foregoing description, it is contemplated that other isoparaifin hydrocarbons may be used or paraflinic hydrocarbon fractions containing isoparaflins. Where it is desired to produce an alkylate comprising mainly constitutents boiling within the range of ordinary motor fuel, it is advantageous to use isobutane or a hydrocarbon fraction containing isobutane in large amount.

Where sulphuric acid is the alkylation catalyst it is desirable to use an acid having a concentration of around to 100% and, preferably, about 94 t0 98% H2SO4.

Ihe temperature of the alkylation reaction may range from around 0 to 120 F., but advantageously is about 60 to 907 F.

Sufficient pressure is employed to maintain .the reacting liquids in the liquid phase.

The ratio of isobutane to oleiins in the charge entering the reactors 1 and I3 is at least about 1:1 and preferably about 3:1 to 5:1. The ratio of acid to total hydrocarbons in the reactor may be around,r 0.5 to 2.0 parts by volume of acid to one of hydrocarbon.

It is also contemplated that other alkylation catalysts besides sulphuric acid may be employed. For example, other catalysts may be aluminum chloride or a liquid prepared by-completely saturating water at about room temperature with boron trifluoride.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. In a process for the manufacture of high anti-knock motor fuel hydrocarbons, the steps which comprise catalytically converting a mixture of carbon monoxide and hydrogen to a synthetic hydrocarbon mixture composed mainly of hydrocarbons having from one to about ten carbon atoms per molecule, said hydrocarbons being composed largely f normal olens, including normal butylenes as the olenic constituents thereof, and being comparatively free from aromatic and naphthenic constituents, separating from said synthetic mixture gasoline hydrocarbons boiling up to about 390 F. having a relatively high content of normal butylenes and a relatively low content of isobutylene as the C4 olenic constituents thereof, and reacting said gasoline hydrocarbons with a paraffin hydrocarbon fraction comprising sobutane in the presence of concentrated sulfuric acid and in the substantial absence of isobutylene and aromatic hydrocarbons whereby sobutane is alkylated to produce normally liquid saturated hydrocarbons having a high anti-knock value and boiling within the range for motor fuel.

2. The method according to claim l in which the conversion of carbon monoxide and hydrogen is effected at a temperature of around 330 to 400 F. under a pressure ranging from about one to ten atmospheres, and with a molal ratio of hydrogen to carbon monoxide of not greater than 2:1.

3. In a process for the manufacture of high anti-knock motor fuel hydrocarbons, the steps which comprise catalytically converting a mixture of carbon monoxide and hydrogen to a synthetic hydrocarbon mixture composedmainly of hydrocarbons having from one to about ten carbon atoms per molecule, said hydrocarbons being composed largely of normal olens, including normal butylenes as the olefinic constituents thereof, and being comparatively free from aromatic and naphthenic constituents, separating from said synthetic mixture gasoline hydrocarbons boiling up to about 390 F. having a relatively high content of normal butylenes and a relatively low content of isobutylene as the C4 olenic constituents thereof, fr-actionating said separated gasoline hydrocarbons into a normally gaseous fraction containing around 50% and more of olens by volume and a normally liquid fraction containing around and more of olefins by volume, separately reacting each of said fractions with sobutane in the presence of concentrated sulfuric acid and in the substantial absence of isobutylene and aromatic hydrocarbons to produce saturated hydrocarbons of high anti-knock value Iand blending the resulting alkylated hydrocarbons to produce motor fuel.

4. In a process for the manufacture of high anti-knock motor fuel hydrocarbons, the steps which comprise catalytically converting carbon monoxide and hydrogen at a temperature of around 330 to 400 F. and under a pressure of around one to ten atmospheres so as to produce a synthetic hydrocarbon mixture composed mainly of hydrocarbons having around one to ten carbon atoms per molecule and comprising normally gaseous and normally liquid hydrocarbons, said normally gaseous hydrocarbons having an olefin content of around 50 to 55% by volume and composed largely of normal butylenes as the C4 oleinic constituents thereof, separating said synthetic hydrocarbon mixture into normally gaseous and normally liquid hydrocarbon fractions, respectively, withdrawing the normally gaseous fraction, reacting said withdrawn fraction with sobutane in the presence of concentrated sulfurie acid and in the substantial absence of isobutylene and aromatic hydrocarbons whereby sobutane is alkylated to produce normally liquid saturated hydrocarbons of high yanti-knock value and suitable for motor fuel.

5. In a process for the manufacture of high anti-knock motor fuel hydrocarbons, the steps which comprise catalytically converting carbon monoxide and hydrogen to a synthetic hydrocarbon mixture composed mainly of hydrocarbons having around one to ten carbon atoms per molecule and comprising normally gaseous and normally liquid hydrocarbons composed largely of normal olerlns as the oleinic constituents thereof, separating from said hydrocarbon mixture a normally gaseous fraction boiling essentially above the C2 hydrocarbon boiling range and composed largely of normal butylenes with not more than a relatively low content of isobutylene as the C4 olefinic constituents thereof, and reacting said separated normally gaseous fraction with a low-boiling isoparafn in the presence of strong sulfuric acid of alkylation strength and in the substantial absence of isobutylene and aromatic hydrocarbons, whereby sobutane is alkylated to produce normally liquid satur-ated hydrocarbons of high anti-knock value and suitable for motor fuel.

ARTHUR R. GOLDSBY. 

